Our aim is to obtain information on the molecular organization of the mammalian urothelium as a basis for understanding biochemcial events associated with differentiation and malignant transformation. We have defined chemically and structurally the unique hexagonal membrane that occurs in mammalian urothelium. We propose to solve this structure at less than 10A resolution by means of x-ray diffraction of isolated membranes. The micellar lipo-protein structure suggested in chemical studies and presented in this proposal should be tested, because it could explain structural conformation changes of biological membranes associated with their functions. Subunits will be isolated and analyzed for protein and lipids and their enzymatic complexes. The role of the Golgi apparatus as the center for membrane subunit assembly will be studied by isolation of a Golgi-rich fraction and examination of Golgi labelling kinetics after short-time incubation of transitional epithelial cells in culture medium containing radioactive precursors of protein and polysaccharides. Parallel studies will be performed with tissue culture cells from human urothelium and from human transitional cell tumors.